Date of Award

December 2019

Document Type


Degree Name

Master of Science (MS)


Environmental Engineering and Earth Sciences

Committee Member

Matthew Cutulle

Committee Member

Rebecca Schmidt-Jeffris

Committee Member

Monica Farfan


Weed management in organic agriculture is one of the greatest challenges farmers face and many rely heavily on mechanical tactics that are labor-intensive and negatively impact the environment. Although more complex, farmers could integrate various cultural, chemical, and biological weed management tools to potentially reduce the need for tillage. A weed management system that incorporates the use of cover crop mulch could suppress weeds and promote weed seed predation services by granivorous insects. Since cover crops decompose as the season progresses, precise applications of organic herbicides could extend weed management towards the end of the season. In our studies, we compare various cover crop mulch treatments to organic herbicide treatments to examine potential synergies between tools, as well as potential non-target effects of organic herbicides on beneficial insects and weed seed biocontrol. We also evaluate the herbicide efficacy of capric and caprylic acid (CCA) compared to conventional herbicides, weeds of different height and species, and at varying pH and concentration. We found that CCA is most effective on weeds <10cm and a lower water carrier pH can increase efficacy. Overall, our work has demonstrated that organic herbicides may be a viable supplemental tool with limited non-target effects, and that combined with other cultural and biological tools may enhance weed control and yield, while reducing soil-borne pathogen abundance and the need for tillage.



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